Increase in lactate without change in nutritive blood flow at active trigger points following massage

A myofascial trigger point (MTrP) is a nodule of tenderness along a taut band of skeletal muscle that may cause pain referral. Massage of the myofascial trigger point (MTrP) results in immediate reduction in trigger point tenderness with reported effects persisting 48 hours, and benefits from multiple cumulative treatments.

The change in tenderness suggests an underlying physiological change, and thus, a study conducted by Albert Moraska and colleagues from Colorado conducted a study in an attempt to understand the physiological change within an active myofascial trigger point undergoing trigger point release (ischemic compression). The study measured changes in nutritive blood flow as well as interstitial glucose and lactate within an active myofascial trigger point (MTrP) following a trigger point therapy massage. The study used a microdialysis catheter that was inserted into an active MTrP of the upper trapezius to allow for continuous sampling of interstitial fluid before and after application of massage.

The study was a randomized, placebo-controlled trial. Subjects were recruited from the general population and conducted at a research centre affiliated with a university hospital. Twenty-five adults (18-49 years old) with episodic or chronic tension-type headache and an active MTrP in the upper trapezius muscle.

Subjects were randomized to receive a single trigger point release massage or sham ultrasound  treatment (as placebo) at an active MTrP in the upper trapezius muscle. Microdialysis was used to continuously sample interstitial fluid from the MTrP before, during, and for 60 min following intervention.

The primary outcome measure was nutritive blood flow within the MTrP as measured by microdialysis ethanol clearance; secondary measures included dialysate glucose, dialysate lactate, and subject discomfort with the procedures. Pressure-pain threshold was determined to assess treatment effectiveness.

The results showed that there was no effect of trigger point massage on nutritive blood flow or dialysate glucose level. However, the dialysate lactate level increased for the massage versus sham treatment. Maximum lactate increase over baseline was observed at 60 minutes after massage. An increase in pressure-pain threshold was significant for the massage treatment.

The apparent inability of massage to elicit a change in nutritive blood flow within an MTrP was unexpected. Active MTrP’s are routinely described as localized, tightly contracted regions within muscle that compress blood vessels causing ischemia although there is no direct evidence. The findings indicate that despite observed physical changes (e.g. tenderness) to the active MTrP from massage, it was not sufficient to alter nutritive blood flow.

The lack of a change in nutritive blood flow or dialysate glucose suggests an alternate source of glucose, such as intracellular glycogen, was utilize generate lactate. Increased lactate is indicative of anaerobic respiration and increased demand for cellular energy, possibly related to a cellular stress response, which requires ATP to remove degraded protein  that could have occurred with treatment.

The authors concluded that massage of an active MTrP affected anaerobic metabolism as represented by an increase in dialysate lactate without change in nutritive blood flow or dialysate glucose.